Olympic and world champion swimmer Cameron McEvoy has broken the men's 50-metre freestyle world record, which had stood for 17 years.

The 31-year-old Australian posted a time of 20.88 seconds on Friday at the China Open in Shenzhen, taking 0.03 second off Brazilian César Cielo's previous mark.

Cielo set his world record of 20.91 during swimming's so-called "super suit" era in 2009. Those suits were later banned because they increased buoyancy and reduced drag, resulting in nearly 150 world records falling in 2009 before being prohibited in 2010.

"I knew I had a chance to do a PB (personal best)," McEvoy said. "My old PB was 21.06, so maybe 20.99? But doing ? 20.88 is unreal. It's crazy."

Cielo was quick to congratulate McEvoy on social media, tweeting: "Congrats, Cam. Lightning fast swim! Incredible!"